Nitrogen recycling in subducted oceanic lithosphere: The record in high- and ultrahigh-pressure metabasaltic rocks

A stable (Li, O) and radiogenic (Sr, Nd) isotope perspective on metasomatic processes in a subducting slab

“…This is in agreement with certain correlations between trace elements and trace element ratios in these rocks that follow seafloor alteration trends (e.g. Nb/U vs. U; Halama et al, 2010).…”

“…Small grey dots are orogenic eclogites (Zack et al, 2003;Marschall et al, 2007b). Dehydration curves were modeled in a similar fashion to the Rayleigh distillation models from Zack et al (2003), MTEC = MORB-type eclogite, AEC = amphibole eclogite, ZEC = zoisite eclogite m = measured; numbers in parentheses give the internal error of the measurement referring to the last significant digit i = initial; initial Sr and Nd isotopic compositions were calculated for T = 130 Ma Rb, Sr, Sm and Nd concentration data are from John et al (2010) and Halama et al (2010) John et al (2010) and Halama et al (2010) …”

“…We investigate a suite of HP metamorphic rocks from the Raspas Complex, Ecuador, which comprises two distinct types of eclogites together with blueschists, serpentinized peridotites and metasedimentary rocks. This sample set has been the subject of several detailed studies in which petrology, major and trace element geochemistry, fluid inclusions and N isotopic compositions have been investigated and where several lines of evidence point toward metasomatic changes Halama et al, 2010;Herms et al, submitted). In this study, we combine stable (Li, O) and radiogenic (Sr, Nd) isotope data with in situ trace element data to unravel the metasomatic effects on the various isotopic systems, which prove to be sensitive to distinct processes happening in the subducting slab.…”

Tracing the effects of high-pressure metasomatic fluids and seawater alteration in blueschist-facies overprinted eclogites: Implications for subduction channel processes

“…These metasomatized rocks may constitute new bulk compositions that can influence the redistribution of major and trace elements (e.g., Bebout, 2007;King et al, 2006;Putnis and John, 2010;Scambelluri et al, 2006), which may be transported over short distances (redistribution on cm scale; e.g., Hermann, 2002;Spandler et al, 2003; or long distances (removal from a system on outcrop scale; e.g., Gao et al, 2007;Zack and John, 2007;John et al, 2008;Spandler et al, 2011). Radiogenic and stable isotope studies in fluid-overprinted metamorphic rocks can provide information about the extent of fluid-rock interactions (e.g., Baker et al, 1997;Yui et al, 1997;Zheng et al, 1999) and the identification of potential fluid sources (e.g., Bebout and Barton, 1993;Halama et al, 2010Halama et al, , 2011King et al, 2006;Scambelluri and Phillipot, 2001;Sadofsky and Bebout, 2004). In principle, fluids in the subduction zone may originate from (I) the partly serpentinised, subducted mantle peridotite underneath the oceanic crust (Hyndman and Peacock, 2003;Ranero et al, 2003), (II) the altered oceanic crust (AOC; e.g.…”

The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)

“…It includes an inorganic component as fixed ammonium, incorporated into potassium sites of minerals and, generally, concentrated in micas, feldspars, and clay minerals. Nitrogen in low-grade metamorphic and igneous rocks occurs as NH 4 + , and in sediments and sedimentary rocks as NH 3 (Wedepohl 1978;Halama et al 2010). The concentration of NH 4 + in igneous rocks is generally related to the kind and amount of the silicate minerals and the ammonium contents that are available for fixation during the existence of the minerals (Stevenson 1962).…”